Abstract:In 2020, concentration of the major greenhouse gases on the earth continued to increase. The global mean temperature was 1.2±0.1℃ higher than before industrialization, ranking the second warmest in the same period in history. Sea level continued to rise at a faster rate.The highest ocean heat content was recorded and the Arctic minimum sea ice range became the second smallest on record, of which record low sea ice extents were observed in the months of July and October. The Antarctic sea ice range remained close to the long term average. Over 80% of the ocean area experienced at least one marine heat wave event in 2020. Areas where “strong” ocean heat waves occur were more than the areas with “moderate” ocean heat waves. On the other hand, many countries and regions suffered from severe torrential rain and floods in 2020, including the Sahel Region of Africa, the Greater Horn of Africa, the India Subcontinent and neighbouring areas, China, Korea, Japan, and parts of southeastern Asia, etc. In addition, severe droughts occurred in many parts of interior South America, while Europe, Australia, Mexico and other places were seriously impacted by severe heat wave events. Moreover, severe cold wave and heavy snowfall were experienced in North America, South America and Australia. Also, there were 30 tropical cyclones generated in the North Atlantic, breaking the historic record.